Two-Year Outcome of Preschool Children With Autism or Asperger’s Syndrome
Peter Szatmari, M.D., Susan E. Bryson, Ph.D., David L. Streiner, Ph.D., Freda Wilson, B.A., Lynda Archer, Ph.D., and Cynthia Ryerse, M.D.
OBJECTIVE: DSM-IV specifies that Asperger’s disorder is a type of pervasive developmental disorder without clinically significant cognitive or languagedelay. There are no data, however, on the outcome of children with Asperger’s disorder or on whether their outcome differs from that of children with autism. The objectives of this study were to compare the outcome of groups of children with these disorders over a period of 2 years on variables independent of the defining criteria and to identify variables that might account for these differences.METHOD: All children 4–6 years of age who came for assessment or were currently in treatment at a pervasive developmental disorder service of one of several centers in a large geographic region were identified. Children who received a diagnosis of autism (N=46) or Asperger’s syndrome (N=20) on the basis of a diagnostic interview and had an IQ in the nonretarded range were given a battery ofcognitive, language, and behavioral tests. Families were contacted roughly 2 years after the date of their enrollment in the study, and many of the tests were readministered. RESULTS: Children with Asperger’s syndrome had better social skills and fewer autistic symptoms 2 years after study enrollment than the children with autism. The differences in outcome could not be explained by initial differences inIQ and language abilities. Children with autism who had developed verbal fluency at follow-up were very similar to the children with Asperger’s syndrome at study enrollment. CONCLUSIONS: Although the exact mechanism for the differences in outcome remain to be determined, it appears that Asperger’s disorder and autism represent parallel but potentially overlapping developmental trajectories.
Children with pervasive developmental disorders demonstrate qualitative impairments in reciprocal social interaction and in verbal and nonverbal communication and engage in a pattern of repetitive, stereotypic activities (DSM-IV). "Pervasive developmental disorder" is a general term referring to a spectrum of disorders that differ with respect to the number or type of symptomsor age at onset. Autism is the best-known example of a pervasive developmental disorder subtype, but, through the years, a number of other subtypes have been proposed as well. These include atypical autism, Asperger’s disorder, and disintegrative disorder (DSM-IV). The diagnostic boundary between autism and each of these other subtypes is unclear and varies according to the classification scheme(1).
Asperger’s disorder is defined by marked difficulties in reciprocal social interaction, fluent but pragmatically impaired speech, and bizarre preoccupations and obsessions. The key features that distinguish autism from Asperger’s disorder are that the latter is characterized by a lack of clinically significant language and cognitive delay (DSM-IV and ICD-10). However, the data on whetherAsperger’s disorder is a valid subtype of pervasive developmental disorder are both limited and inconsistent (2, 3).
Although there are several outcome studies of children with nonautistic pervasive developmental disorder (4–8), no study has specifically examined Asperger’s disorder. Now that many more children are receiving this diagnosis, outcome studies are essential to evaluate the clinicalusefulness of the category and to provide information to parents. In a previous publication based on cross-sectional data (9), we reported that 4–6-year-old children with Asperger’s disorder have better language and socialization scores and fewer autistic behaviors than children with high-functioning autism, but whether this is a useful distinction depends, in part, on outcome evaluations.